Ammeter wiring - '82 90HP

[interalian]

Still working on the old boat - may get it on the water yet, but still on vacation on Maui.

When originally rigged, the ammeter was wired in a way that only shows discharges from accessories, and I would like to have it show charging as well. Is there a practical way to do this? I don't mind tapping into the motor wiring harness or rewiring the panel as needed.

The original non-motor loads run off separate leads (fused), directly at the battery, nothing tapped into the control box.

 

[gm280]

Usually the gauge is installed in the positive wire running from the battery. That way if the battery is charging, it reads a positive current. And if it is discharging, it reads a negative current. Pretty simple setup... Just make sure the gauge can handle the total charge and/or discharge that can possibly happen. Usually the Ammeter uses a shunt to handle the huge amounts of current. So just make sure your gauge can handle those currents.

 

[emdsapmgr]

You may want to consider changing the ammeter for a volt gauge. Most boat applications have discontinued the use of ammeters for the reason that gm280 cites. The voltmeter is an acceptable measure of battery charging and battery health. Now found on most marine setups with the normal set of typical gauges. Much easier to setup, just connect direct to the battery.

 

[interalian]

See photo in first post. There's a volt meter already. I'll probably just leave it alone...

 

[F_R]

Without a wiring diagram specific to the motor, I can only give a generic answer. Basically, you have to disconnect the small red wires from the starter solenoid and extend them all the way forward to the GEN side of the ammeter. Then run another wire from the BAT side of the ammeter all the way back to where you took the wires off the solenoid. Use at least 10 Gauge wires for this.

All other loads that you want to register on the meter should be connected to the GEN side of the ammeter.

The real reason they quit using ammeters is $$ and bulk. All that 10GA wire adds up. And if you cheat and use too small wire, you start getting voltage drop problems.